Although thermoplastic resins and their applications are well known, reinforced resins are relatively new and have significant advantages over pure, resinous composites. Fiber reinforcement toughens and stiffens the resin to produce high performance products. At the same time, processing is not seriously hindered because the reinforced resin maintains its thermoplastic character. For example, a sheet of fiber reinforced resin can be heated, stamped into a desired shape by appropriate dies, reheated and restamped to alter the shape. In contrast, a thermosetting resin cannot be reshaped, once it is fully cured by heating. Thermoplastic resins however, generally exhibit poor solvent resistance, and this deficiency has severely limited their use. For example, reinforced thermoplastic resin circuit boards of conventional design cannot be cleaned by solvents commonly used in the manufacture of circuit boards. Hydraulic fluids and cleaning fluids in aircraft limit adoption of conventional thermoplastic resins unless their solvent resistance can be improved.